Commutator blank and method of making commutators



J. KLYM Sept. 15, 1953 COMMUTATOR BLANK AND METHOD OF MAKING COMMUTATORS Filed Oct. 19, 1950 INVENTOR. J/uus KLYM WWW V Arroeways Patented Sept. 15 1953 COMMUTATOR BLANK AND METHOD OF MAKING COMMUTATORS Julius Klym, Cleveland, Ohio, assignor to Kirkwood Commutator Company, Cleveland, Ohio,

a partnership Application October 19, 1950, Serial No. 190,977

7 Claims.

This invention relates to commutators, particularly to a new type of a commutator blank and to a method of making commutators.

Heretofore one widely used method of producing commutators for electric motors and generators and other similar uses, has been to produce a large number of relatively elongate commutator blanks, which usually are made from a strip of copper that is punched or blanked in order to form a large number of similarly shaped commuator segments from the copper bar. To make a commutator from such commutator blanks, a worker takes a commutator blank and positions a strip of insulating material, such as mica, adjacent one side of the commutator blank, then next positions another commutator blank against a side of the mica insulation strip, then proceeds to complete the annular assembly of alternate strips of insulation and commutator blanks which are wedged fairly tightly together. The associated commutator segments and insulation strips are then completed to commutator form. This completion. of the commutator has comprised either embedding the assembled commutator pieces in a plastic insulation medium, such as Bakelite, by a molding operation, or else the loose assembly of commutator segments has been bound permanently together by the use of an iron or other type of metal mounting sleeve which is inserted through the commutator segments and 'peened over or otherwise brought into engagement with opposite end portions of the commutator segments to retain them in a desired fixed relation to each other. I

While the previous methods for producing commutators has yielded desirable types of commutators, such commutators and methods of assembly have been objectionable because of the relatively high'cost of such commutators and particularly of the specific type of insulation normally used in commutator manufacture i. e. mica and because of the large amount of hand assembly labor required.

At least one previous effort has been made to eliminate the use of mica strips in forming commutators and such previous method is disclosed 'in British Patent No. 584,867. This previous British patent, in general, provides a commutator which is formed from a relatively thick metallic strip. The metal strip is provided with a 60 plurality of parallel transversely extending slots formed in one surface thereof so as to form a plurality of lugs, or projections that extend from one side of the continuous metal strip. In some formed in the projecting portions provided in the metal strip by the transversely extending slots. Then to form a commutator from such specially shaped metal piece, the correct length of the preformed metal bar is bent into annular rorm after which a suitable plastic material is molded into and around the metal strip segment, which now is in annular form and has the different lugs provided therein extending radially inwardly Irom the continuous base portion thereof. Individual commutator segments are then provided by turning off the peripheral portion of the metal strip until the continuous base portion of the strip has been completely removed so that only the individual transversely extending segments of the original metal piece remain embedded in the molded plastic material. This type of production of commutators has involved the use of several different pieces of apparatus for preforming the metal strips to desired shape for forming the different commutator segments therefrom, and several cutting or shaping operations.

The general object of the present invention is to provide a novel type of commutator which is made by'a new method that is characterized by the efficiency of operations in such commutator forming method and by the low cost of the commutator and its assembly.

Yet another object of the invention is to provide a commutator the individual segments of which are insulated from each other by the material in which the commutator segments are embedded.

A further object of the invention i to provide a commutator making method wherein specially shaped segments are used in producing the commutator and wherein such specially shaped segments reduce the number of operations required to assemble the commutator segments in condition for a molding operation to deposit an insulating and binding plastic material into and around such segments.

Another object of the inventionis to provide a commutator producing method which uses only a minimum of procedural steps in the production of commutators.

Another object of the invention is to provide a novel type of a commutator segment wherein the commutator segment has generally triangularly shaped sectional contour and wherein a longitudinally directed laterall offset portion is provided on the commutator segment at the base thereof.

Still another object of the invention is to proinstances, longitudinally extending slots are also vide commutator segments which are adapted to be positioned in a commutator assembly rin in which relationship to each other only the base portion of the commutator segments contact each other.

The foregoing and other objects and advan-. tages of the invention will be made more app ent as the specification proceeds. I I

For a better understanding of the invention, reference is directed to the accompanying drawings, wherein: I I I I Fig. 1 is a perspective view ofa metal bar used in forming commutator blanks or segments of the invention; I I I Fig. 2 is a side elevation of, a commutator-blank of the invention with other blanks being indicated adjacent such blank to indicate how the bar shown in Fig. 1 would be severedtoproduce the commutator blanks;

Fig. 3 is an end elevation of the commutator an s F l U II F 5 s a. e tion .tbtbl hf ns m in h r e s of ..m i qiurelin'.iaq q with the p i p s. o .t e reseet re e e I I Fig. 5 is a section similarto g. 4 of 'a coinpleted commutator of the i r iv entn; I

Figs 6 nd are. n elev i'idnl ied i tions of thecommutator blanks of the invention; and

.7 Fig. 8 i a fra n ary a ra i n .d yte l ther modified typ e of commutatorsegments showing them in assembly in a confining ring.

e present i e 'na b oad Sense. r lat to the provision of a new type of commutator blanks whichhasa laterally ofifset portion in la base on. f h blank rwhereb ne rzli fe ty b blanks can be assembled in annular form in a retaining ring and be wedged thereinto only the base portions of the commutator blank s contacting and with the "radially inner portions thereof being circumferentially spaced from each other. Next the commutator segments would be embedded in agnoldable insulation material by a suitable moldin no erationwhile the segments are retained in their'annular form, after which the peripheral portion of the so f QIm ed commutator blank would b e-turned off orotherwise removed to cut away the peripheral-portion of the molding material andthe base portions of the commutator segment to leave only the portions ofthe commutator segments which are inspacedrelationship;to each other, I

Reference now is directed to the details o the figures shown in the drawings andF g. 1 illustrates anelongate metal bar 10 thatgis of generally frusto-triangular shape :in cross section and which bar is made fromsome-goodelectrical conductorysuch as copper or silver or al y or such material. Th'efmetal 'bar ll] :is:shown as having'a base I'Lapair of sides "and I3 and an apex [4. Figs. land 3 best show that, the metal bar II] also has a longitudinallyextending, laterally outwardly. ofiset section ['5 extending the length thereof formed "at the base portion of the side [3.

In order to form a plurality ofcommutator blanks, or'segments, or bars from the metal bar ID, the metal bar In is fed into a punch press or similar device bywhich a plurality of commutator segments or blanks generally indicated by the numeral I6 are produced. The sections of the blanks l6 are identified by the numerals I2,'l3, l4 and l 5, used to refer to thecorresp onding portions of the metal bars Ii], and the base II is also so identified in the segments it. 'It will be seen thatapluralityof similarlyshaped 'ta'ining ring I 8.

1y of the'blanki lll from the .o t

blanks can easily be formed from the metal bai II] with a minimum of waste of the material comprising this metal bar.

Preferably in forming the commutator blanks IS a tang I1 is formed in the commutator blank at the apex l4 thereof and this facilitates embedding the commutator blanks insac'onimutator, as hereinafter described.

-After a plurality of the commutator blanks I5 are provided, these blanks are then, usually manually, positioned within a confining or re- The original size and shape of the metal bar In and the commutator blanks IB fQrmed the refrOin are predetermined with relation to the diameter of the ring l8 so that the commutator blanks It can be abutted against each "other in the ring 18 and can be wedged into position therein with a predetermined number of blanks It being positioned within the ring I8 vvithbnly the oifsetsections [5 off "the commutator blank een'taezm ea h other whereas the remaimie'r' of the Itand [3 of the blanks win be in i'r'eumrere tial y spaced relatio'nto each other, insof r as adiacent surraeesor adjacentcommutatorblanlisare concerned. I II I Fig. 4 or the drawings showstnatan insure tion nateri al T9 is "positioned intermediate adjacent side'sur'faces oftliefcommtato'ri, III I t andalso is pss'itie'ned radially inwardly therefrom. Usuallytheend portions'or tire conin tator blanks it are also embedded nthein tion material. 'Any de ir d typeo'r ineidabre sulation material normally can he uses fs'o as t mbed the commu at r-"blanks It in the re;- sultant memeaeroaua "whichcoinpri'sesfal rou commutator. I The rough eommutateaprcommutator 'b aiik,

shown in Fig. 4 is suitably remevea ram-tire ri g l8 after which it"usua'lly is' 'posit n-edfby'a chuck or equivalent device which'e I I a'bore 20 oftlie roughcoinmiitatoi', and the'c 'in mutato'r rotated in a lathe or *other "equivalent device so that a suita ieieiiamg or'g'rmaisgtapi can be brought into en agement with the riphery er the commutator n order to on on the base port ons r the commutats "blanks its and completely remove the offsts'ctinfi Hence only the circumfefentially'spacedpoftions of the original commutator bl 'nks IE ar Ieft in the. resultant commutator. 'It Iiivill b' n 613 met some er the insulation'inatrial is. d1" the bases of the blanks will alsobe r in thesame operation. I I I 7 It W111 be appreciated'that'the'oiist p I of the commutator segment or "blanks [.6 ma be of any desired size and that they need be continuous over the length .of the blankl Fig. 6 of the drawings shows a fno'dififed, of commutator blank 30 "therein. Int 1 stance the blank isiof generally 'thes'arne I as theblank is only it isprovided with} rrs't portions 3| and 32 one of is on each side surfaceof the blanks I31]. I

Fig. 7 shows yet anotheritype ofja il IL f orming blank 40 -which is provided with an on,

al ds llv. eeef id 99 h? ak i-ki u d b n t d th th l teral y Ie e 42 of the offset M is preferablytapered n but'that in this instance the I I of'the eem'imitator'b ji oinprises, par 11c pertien swnereasii ualiyt invention have inwardly ta it? pered side surfaces.

face 42 will not intersect the commutator blank 4|] sothat when a plurality of suchcommutator blanks are positioned within a retaining ring in side by side relation, only the offset portion thereof will contact the. adjacent commutator blank.

Still another modified type of commutator blank is shown in Fig. 8. In this instance, a commutator blank 58 is shown wherein the sides of such blank 50 are converging toward each other more sharply than do radially extending lines in the commutator into which su'chblanks are to be assembled. In this instance also, the sides of the blank 5|] are shown as coming to a sharp point on the radially inner ends thereof although normally the commutator blanks are of frusto-triangular shape since it is not real desirable in many instances to have sharp inner surfaces on the commutator blanks. These commutator blanks 50 are shown in assembled relationship in a retaining ring 5| into which a plurality of the blanks 50 can be wedged.

It will be seen from the foregoing that in assembling a commutator in accordance with the invention, the worker does not have to assemble any insulation strips or sheets between the different commutator blanks so that this operation is avoided. The removal of the base portions of the commutator blanks does not actually require much additional time over the normal rough out that is taken on the periphery of a commutator by the manufacturer thereof prior to shipping same to the person who will assemble such commutator in an electrical device. Hence it is submitted that the objects of the invention have been achieved and that a novel type of commutator segment and commutator forming method have been provided.

While several complete embodiments of the invention have been disclosed herein, it will be appreciated that modifications of these particular embodiments of the invention may be resorted to without departing from the scope of the invention as defined by the appended claims.

Having thus described my invention, what I claim is:

1. That method of making a commutator comprising the steps of forming an elongate metal bar of substantially triangular cross sectional contour, which bar has a laterally ofiset section at its base, blanking a plurality of commutator segments from the metal bar, arranging a plurality of commutator segments in annular form with their side edges abutting each other at least at their offset sections and with their apices extending inwardly of the ring and being spaced circumferentially thereof, encompassing the positioned commutator segments in a plastic insulation material that is positioned intermediate the adjacent side edges of the segments except at the offset sections thereof to form a commutator blank, and removing the peripheral portion of the commutator blank including the offset sections of the commutators segments to form a commutator.

2. That method of making a commutator comprising the steps of forming a plurality of commutator segments of substantially triangular cross sectional contour, which segments have laterally offset sections at their bases, arranging a plurality of the commutator segments in annular form in side by side relation with their side edges abutting each other only adjacent their bases and with their apices extending in wardly of the ring and being spaced circumferentially thereof, encompassing the positioned commutator segments in a plastic insulation material that is positioned intermediate the spaced adjacent side edges. of the segments to form an annular commutator blank, rotating the commutator blank about its axis, and cutting off the peripheral portion of the commutator blank including the ofifset sections'of the commutator segments to form a commutator.

3. That method of making a commutator comprising the steps of confining a plurality of commutator segments of substantially triangular cross sectionalcontour, which segments each have a laterally offset section at its base in annular form with their side edges abutting each other only at their offset sections and with their apices extending inwardly of the ring, molding insulation material around the positioned commutator segments, and removing the peripheral portions of the molded commutator segments including the offset sections of the commutator segments to form a commutator.

4. That commutator making method comprising assembling a plurality of tapered commutator bars having base and side edges and an apex with their base edges in contact in annular form with at least the radially inner portions of their side edges spaced circumferentially from each other and with their apices being radially inwardly of the so-formed ring, embedding the commutator bars in a, moldable insulating material, and cutting away the contacting base portions of the commutator bars and any insulation material radially therebeyond to leave a plurality of spaced commutator bars embedded in the insulation material.

5. That commutator making method comprising assembling a plurality of commutator bars having base and side edges with their base edges in contact in annular form with at least the radially inner portions of their side edges being spaced circumferentially from each other, embedding the commutator bars in an insulating material, and removing the contacting base portions of the commutator and any insulation material radially therebeyond to leave a plurality of spaced commutator bars embedded in the insulation material.

6. That commutator making method comprising wedging a plurality of commutator bars having base and side edges and an apex in a ring form with the radially inner portions of their side edges spaced circumferentially from each other and with their base edges being in contact to retain the bars in their given positions, embedding the commutator bars in a moldable insulating material, and removing the contacting base portions of the commutator and any insulation material radially therebeyond to leave a plurality of spaced commutator bars embedded in the insulation material.

7. That commutator making method comprising wedging a plurality of commutator bars having base and side edges and an apex in a ring form with the radially inner portions of their side edges spaced circumferentially from each other and with their base portions being in contact to retain the bars in their given positions, embedding at least the radially inner portions of the commutator bars in a moldable insulating material, and removing the contacting base portions of the commutator bars to leave a plurality 

